The haptic interfaces are systems implementing a set of techniques deriving notably from robotics and computing. These systems make it possible to physically stimulate a user through tactile and kinesthetic and/or thermal perceptions and allow for a better immersion in virtual environments representative or not of real environments.
Thus, the haptic interfaces act on the user by applying to the user forces, vibrations, movements, or changes of temperature making it possible to feel textures, shapes, forces or heats.
By way of example, the CyberTouch (registered trademark) system developed by the company CyberGlove Systems consists in wearing a data glove equipped with vibrators making it possible to stimulate the phalanges and the palm. This type of system has the drawback of being particularly intrusive.
Another example of haptic interface has been proposed in the article by H. Takayuki, T. Masafumi, I. Takayuki and S. Hiroyuki entitled “Noncontact tactile display based on radiation pressure of airborne ultrasound”, IEEE Transactions on Haptics, vol. 3 no. 3, pp. 155-165, 2010. It is proposed to exploit the pressure of the acoustic radiation generated by ultrasound transcoders in order to stimulate the user. This makes it possible to implement a haptic interface without direct contact with the user. This interface is based on the control of the phase delays of the acoustic waves to produce a focal point. The main drawback with this technology relates to the limit of intensity of the force applied to the user. Another not-inconsiderable drawback is that it can lead to medical risks, particularly in interactions with sensitive regions such as, for example, the head or the face.
Another example is based on the use of a plurality of air jets as presented in the article by Y. Suzuki and M. Kobayashi entitled “Air jet driven force feedback in virtual reality”, IEEE Computer Graphics and Applications, pages 44-47, 2005. This paper discloses a haptic system consisting of multiple air jets arranged in a matrix and rigid air receivers held by the user. The air jets released through nozzles strike the air receivers and apply forces to the hand of the user. This haptic device allows a user to interact with static or dynamic surfaces. This strategy presents the notable drawback of a limited resolution in terms of force and position. Furthermore, the user has to be provided with at least one effector, that is to say a rigid air receiver for example.
It appears that none of the haptic systems mentioned above make it possible to both dispense with any direct contact with the user while allowing hazard-free access to a great wealth of rendering and perception such as a volume perception, a three-dimensional gestural guidance, etc.